DE2327528A1 - Composite saw blade strip - tooth material appled to backing by powder metallurgy and compiste rolled - Google Patents

Abstract

Tooth material in powder form is packed between two side-by-side bodies of backing material in an air-tight container which is evacuated and sealed before being isostatically hot pressed. The bonded product is rolled to a composite strip having a central band of tooth material, the strip finally being split to form two lengths of saw blade stock.

Description

Method for making bimetal band saw blades The invention relates to the production of bimetal band saw blades for cutting Netall with sawtooth bits made of high-speed steel, such as M2 or the like and a 3and part made of durable steel with the sawtooth feet. Medium Carbon steels and low-alloy steels like the D6A have the required Fatigue strength for continuous bending during operation of a band saw blade.

The products made by the process of U.S. Patent 2,786,788 are examples of the 3-metal band saw blades considered here0 The task The invention is to provide vastly improved bimetal band saw blades from an in bimetal raw material produced in a new way, in which a complete, flawless connection between Since the two different networks are created, professionals have long known that attaching the tooth tip netall to the band metal posed the most difficult problem the production of a bimetal band saw blade is.

Prior to U.S. Patent No. 2,786,788, the industry was disappointed when looking for a satisfactory bimetal band saw blade. Anderson's first in the above

Patent proposed electron beam welding of the two types of steel made it possible for the first time to produce a bimetal band saw blade economically However, such a method is very costly and often encounters unpredictable ones Procedural difficulties. despite particularly great attention to all procedural steps It is often found that there is sometimes a bad connection between the quick sonic steel wire and band metal. It was therefore after a Wanted a better way of joining the two metals and according to the present Invention also found0 The answer to this problem lies in the discovery that with hot isostatic pressing (hot isostatic pressy), following Called HIP process, pre-alloyed powdery cutting steel with either also pulverulent or solid rods present band metal combined can be used to produce one-piece plates that can be rolled out to form bimetallic strips kann0 The HIP process as described in ASME Publication 71 WÄl PROD 20 from ASME Winter Congress in Washinton D.C. from 28e11t to 02/02/1971 is used for solid diffusion bonding or the union of components of different All an inert gas pressure at elevated temperatures.

This HIP process allows powdered metals and others Compress substances either in loose form or in the form of a cold compact body and connect. The materials to be treated are placed in an airtight container enclosed by appropriate geometric dimensions, which then evacuates and sealed and placed in a pressure vessel in which the container is included its contents are exposed to heat and pressure at the same time. Mostly will an inert gas is used to generate pressure in the boiler. For heating the contents of the boiler can use any means to come into use. With the HIP process know that much higher clearances can be achieved than with any other method.

On the basis of the above, the invention will now be based on the following Description and the drawings are described by way of example. Without from the crux It will be understood that deviating from the invention as set out in the following claims Changes in the exact implementation of the procedure and the training of the corresponding devices.

In a preferred embodiment of the invention, the tooth tip is metal used in powdered state How in detail this metal powder is produced Rein is part of the invention. It can be a conventional procedure Act. The dmetall that forms the back of the saw band is - although it is also powdered State could be used - preferably in the form of solid rods of smooth Cross-section used. Compared to previous manufacturing processes for saw band raw material for the metal that forms the back of the saw band is required in band form through the use of rod-shaped Starting material not only a reduction in material costs, it also becomes possible to use raw material of various origins to bring into use 0 After appropriate cleaning of the Surfaces become two or more vertically aligned bars of the strip metal arranged equidistantly in a straight row.

The spaces between adjacent rods are down and on the sides I am locked. This is most conveniently pushed by using metal plates attached to the bars that bridge the intermediate rails or by using a bottle wall elongated, upwardly open metal container used and the rods of the strip metal so inserted into the container that they stand vertically on the container bottom and lie flat against the side walls. This arises between the neighboring bars at least one vertical chamber.

The tooth tip-forming alloy powder (M2 or the like), the one beforehand with a variety of dispersoids or other alloy-supporting materials Mixing additives is now in the chamber (s) between adjacent rods of the strip metal poured in to then, for example by welding, a cover plate firmly on the Attach top of chamber (s) and make an airtight To form a casing for the powdered tooth tip metal, but in the lid Evacuation openings are provided, through which the powder-filled chamber (s) can evacuate at the most favorable temperature and pressure, if this happens the evacuation openings are closed.

In this way, a bimetal assembly has now been created that can be hot isostatic pressing. The tri-metal assembly is used as part of the EIP technology exposed to an elevated temperature and high pressure in a pressure vessel.

The residual air is preferably removed from the pressure vessel beforehand in order to increase pressure and temperature at the same time so that disturbing convex currents become minimal.

By this hot isostatic pressing, the pulverized tooth tip material becomes compressed and connected to the strip metal. The result is a one-piece Metal plate of exceptional quality.

Because compacted powdered metal has nearly a hundred percent Density with an exceptionally fine grain structure and barely noticeable segregation.

The temperature and pressure to which the boiler contents are exposed, The purposes of the present invention depend on the material to be treated have a temperature between 9800 and 12300 C and a pressure between 1000 and 2100 atm proved to be useful.

However, it is known to the person skilled in the art that lower temperatures can also be used can couple with lower Irtloken with higher pressures or higher temperatures. The handling time for the bimetal assembly in the pressure vessel depends on its size from and also on whether pre- and / or post-heating is carried out.

After annealing, the bimetal plate obtained from the HiP process becomes further processed to a bimetallic strip in which a narrow central section of the tooth tip metal lies between broad sections of the strip metal. To this Purpose one preferably leads the plate between rollers so that the separation point between the two metals is aligned perpendicular to the roll axes.

It does not matter whether the bimetal assembly only has a central section made of tooth tip metal between two strip metal sections or a multitude of such Arrangements contain A, the assembly should always be designed in such a way that that the subsequent rolling out into a strip results in a tension equalization comes. In the case of bimetal assemblies with only two strip metal rods, this is done on the easiest by having both rods with the same rectangular cross-sections and of the same length if the bimetal assembly consists of a plurality of pairs of strip metal rods exists, men can obtain the desired equalization of tension by being symmetrical builds up and a corresponding dimensioning of the relative quantities and / or thicknesses of the adjacent strip metal bars makes a Even if the rolling mill specialist knows that it is advisable to anneal steel plates several times during rolling and also when Must be annealed, it should be mentioned here for the sake of completeness that preferably annealing is carried out immediately before the last rolling process, as the result of the rolling process Adjusting curing the entire strip on one for each one used Alloys brings the desired hardness. In the present invention, the lack leads a mixed characteristic in the fusion zone to shorter annealing cycles and thus to an improvement in profitability.

Either before rolling out or at any intermediate stage of the The rolling process, the press container is removed from the plate. This can be anything for example done by conventional etching.

When the desired reduction in area is achieved, the rolled out strips simultaneously in the middle of the narrow middle section3 and outside of the central section divided in the longitudinal direction, by two lengths of one Bimetallic starting workpiece of coated width ru obtained, with each of the Edge of each length with that initially in the pulverized state present tooth tip metal is connected.

After the starting bimetal strip is annealed, cut to size and has been smoothed and also the trailing edge of the tape ticking by sanding or the like. Has been finished processed, the final band saw blade can be produced. For this, it is only necessary to insert the metal into the tooth tips Strip edge to cut the teeth eo that only the tips of the teeth from the beginning powdered metal.

Then the teeth are straightened and set.

by hardening and tempering the saw blade thus formed corresponding the instructions in the USA patent mentioned in the introduction is the bimetal band saw blade Completed Due to the internal tension equalization, which is created by ente speaking Construction and geometric dimensioning of the bimetal assembly results is the ripping and straightening is made much easier.

As mentioned earlier, it can be used for hot isostatic pressing provided bimetal assembly is a single spaced-apart pair of strip metal rods with an intermediate corresponding amount of the powdered tooth tip metal or contain a plurality of such pairs of rods. In the latter case deliver all strip metal bars except for the bars on the very outside of the row of raw material strips for two bimetal band saw blades each0 This means that the Bimetal strips not just the narrow sections of the tooth tip metal but also split the wider sections of the strip metal.

The straightness of the bimetal strip before it was divided in the longitudinal direction is especially important. Therefore that can Creation of curvatures should not be tolerated when grooming the metal plate. The bimetal assembly must therefore be designed symmetrically at least with regard to their internal stresses. To ensure straightness after cutting lengthways, should Geometry and cross-section of the two solid strip metal bars that make up the initial flanking powdered tooth tip metal strips, be identical.

Another important parameter is the parallel and plane relation the interfaces between the two metals.

This requirement is most easily met by using the Tape metal used for the assembly to be assembled initially, rigid rods. The opposing flat and parallel interfaces of the two rods automatically ensure the desired relationship.

According to the invention, in the manufacture of the bimetal assembly but a powder can also be used for the metal forming the back of the saw band In this case, the two metals must do so during hot isostationic pressing enclosing housing a complete container with a flat bottom and shallow Front and side walls be. The required parallel and plane Shape the interfaces between the two. Metals results from insertion flat, parallel dividing strips in the container, the edges of which the Touch the side walls of the container. These strips can be made of a metal which has the same composition as one of the metals to be joined for tooth tips and tape. During the hot isostatic pressing, the parting strips then become stronger Part of the bimetal plate.

The dividing strips could also be dropped if one or both of the powdered metals in pre-pressed strips and / or bars of the appropriate Bringing geometry to use.

As before, the container holding the powdered metals can be dimensioned so that it contains a number of alternately arranged metals for the Tooth tips and for the back of the saw band, so that after the longitudinal cutting more than two of a bimetal band saw band starting workpiece arise, as below It will be even more evident that brings the use of both metals in powdered form State with an intermediate separating strip and / or one or both powdered metals in the pre-pressed state the advantageous possibility of regulate the chemical structure at the transition points. This pushed through a corresponding grading of the powder metallurgy building materials.

Although the invention is certainly already clear from the foregoing Description is to be found in the following with reference to the accompanying drawings be described again in more detail0 The drawings show in examples different, presently preferred ways of performing the invention Procedure as follows: Pzigo 1 a short section of a bimetal band saw blade, which is to be improved by the present invention, Fig. 2 is a side view a short section of the bimetal starting material for the manufacture of a Bandsaw blade according to Fig. 1, Fig. 3 is a top perspective view on a bimetal assembly to explain the creation of a container for the powdered tooth tip metal, Fig. 4 is a top perspective view the upper end of the assembly of FIG. 3 in the evacuated and sealed state immediately before being introduced into the pressure vessel in which the hot isostatic Fretting takes place, FIG. 5 is a schematic representation of two bimetal assemblies in the pressure vessel, Sig. 6 a perspective partial view of a bimetal plate from which the band saw starting material is manufactured Fig. 7 a more or less schematic perspective illustration of the rolling of the bimetal plate to one Bimetallic strip, FIG. 8 shows a perspective partial view of a bimetallic strip according to rolling out the plate according to FIG. 6, 9 shows an illustration of the longitudinal division of the bimetal strip, Fig. 10 is a perspective view of a More economical wide bimetal assembly with several in alternating order arranged metals for tooth tip and band back formation, Fig. 11 is a perspective Partial view of a tielfach-bimetal strip as a result of the rolling out of a the assembly according to FIG. 10 produced by hot isostatic pressing plate 9 Figure 12 is a perspective view of the upper end of a container with the removed Lid to form a bimetal assembly in which both metals are initially pulverized State, and FIGS. 13 and 14 boundary transition profiles of alloy components Fig. 1 of the drawings shows a bimetal saw band with tooth gaps 3, the actual one Band or saw band back 4 and saw teeth 5. Area 6 with band 4 and tooth bases 5 excluding the tooth tips 7 is made of medium carbon steel, weak alloy steel, such as 16A, or some other good band saw blade metal with good fatigue strength. However, the tooth tips 7 are made of high-speed steel or the similar steel, saw band the Sig. 1 was made from the bimetal blank produced according to FIG. 2, in which an edge part 8 made of Sohnell cutting steel and the remaining part of the strip made of low-alloy medium carbon steel, such as D6A, exist.

The saw teeth are cut into the saw band blank in the usual way Milling incised. To do this, a group of blank lengths is clamped together and then lets the milling tools on the edge of the belt through the Sonell cutting chair Cut through it so deep that only the tips of the teeth are made of high-speed steel. Before the milling process, the pimetal blanks were annealed.

As explained above, the band blanks are produced by that the bimetal strips 9 of the Pig. 8th in the longitudinal median plane divided parallel to the edges.

The bimetal strip is the result of a rolling process in which one sends a bimetal plate 10 through a grater of rollers 11 as it does is shown schematically in FIG. Here it is important that the parting line between the metals forming the plate runs perpendicular to the roll axes.

In one embodiment of the invention, the first step is in the manufacture of a bimetal plate 10 (Fig. 6) in that you have two rods 12 from base metal, i.e. here from the metal from which the back of the saw band is made is arranged parallel to one another, as shown in FIG. 3, and in the same way Flat side surfaces of the rods steel plates 13 are welded. Also to the Bottom surfaces of the rods 12 and on the lower end surfaces of the steel plates 13 Another plate 13 'is welded on. This creates between the opposite surfaces of the rods a chamber 14, which is filled with the powdered, the metal 15 forming the tooth tips is filled. To prevent that in that Bimetallic strip to be produced later when rolling out Sxümmunden must be Bimetal assembly with the two rods 12 and the metal powder 15 in between a have symmetrical cross-section. This is the easiest to do achieve by giving the two rods the same cross-section and adjusts their opposing surfaces exactly parallel.

The width of the space between the rods 12 is determined in the Bimetal strip 9 the width ratio of narrow middle section 16 (Fig. 7) of the tooth tip metal to the wide flanking portions 17 of the strip metal. Therefore, this gap is not made wider than necessary in order to achieve the proportional volume or amounts of the tooth tip metal in the bimetal plate get. The middle section 16 must provide two shrouds forming tooth tips, namely one edge for each of the two partial stitches of the bimetallic blank, which arise after the length cutting.

When the powdery tooth tip metal is poured into the chamber 14 is, the top of the chamber is made by welding a lid 18 onto the tops of the rods 12 and the adjacent ends of the side plates 13 (Figs. 3 and 4) closed. On the cover 18 there is a suction connection 19 with a metal tube 20 for connection a vacuum pump or other suction device. After this the Chamber 14 is evacuated, the tube 20 is closed by a constriction 21, as Fig. 4 shows.

The chamber 14 is now sealed.

The now finished bimetal assembly is now in a pressure vessel 22 and hot isostatically pressed there. The schematic drawing 5 shows how two such assemblies can be accommodated in one boiler. According to the HIP technology explained in the introduction, the interior of the pressure vessel is - after it has been cleaned beforehand - heated up and exposed to high gas pressure, the temperature in the boiler being suitably 980 to 12300 C and the pressure can be brought to 1000 to 2000 atmospheres. Understandably, the temperature increase is allowed do not take place so quickly that it leads to undesirable thermal stresses in the Assembly is coming. Rather, the heating process should proceed in such a way that it becomes uniform The bimetal block must be at the selected temperature and hold the selected pressure long enough to achieve full compaction of the powdery tooth tip metal and its boundary layer to the strip metal received0 According to a specific example, in a pressure vessel with an inner diameter of 66 cm and a length of 152 cm in one hour Working cycle of fifteen bimetal assemblies, each with four bars of the strip metal with a cross section of 5.7 cm and a length of 145 cm at a mutual Distance of 8 powdered tooth tip metal arranged in and in the interstices be pressed evenly and isostatically hot to form bimetallic plates. The bimetal assemblies are preheated to 650 ° C before being introduced into the pressure vessel and then at sealed pressure vessel to a maximum temperature within about two hours of 11500 c when pressurized by an inert gas up to 1000 atm. This operational data can last for a period of an hour or two are maintained, the boiler contents are assumed to be at the temperature mentioned Has.

With the rolling out of the bimetallic plates to the elongated bimetallic strips 9 (Fig. 73 can be started before removing the side panels 13. These However, the side plates should be removed before the whale gate is finished Bef the longitudinal division of the bimetal strip shown schematically in FIG. 9 in two lengths of a bimetal saw band blank must be carefully taken into account that the shear rollers 22-22 'or their equivalents exactly in the middle of the narrow central section 16 of the strip and that the two trimming cuts are also parallel run to the middle cut.

An electronic track follower can be used to meet this requirement use which follows one of the dividing or transition lines and ensures that that over the entire length of the strip each piece of tape material has a very specific one Tooth tip piece comes.

If the bimetal plate produced according to the invention consists of several pairs consists of band-forming stays and intermediate tooth tip metal, one can they address as a multilayer sandwich arrangement. Here you can use the required The best way to encase the tooth tip material is to have wide side plates welded to the surfaces of the rods arranged in the same plane and one long base plate provides that on the undersides of the side plates and the undersides welded to the outermost rods will, to close all the chambers between the bars on the sides and below. Afterward can then put a lid on the tops of the side panels and the furthest outside lying bars are welded on.

Another possibility is to use a full one Metal container 25 or the like. As shown in FIG. 10. This container 25 has flat side walls 26 which are connected to end walls 27 and a base 28.

The side walls are so far apart that they taut the bars 12 can accommodate between them. The front walls 27 are sufficiently far apart, the desired number of pairs of rods and required spaces between these rods 12 in a row of spacers 29 on the floor 28 in the correct position Kept their distance. The spacers 29 should not be too far between the individual Rods protrude upward into the chambers 30. A lid 31 is attached to the side and End walls 26 and 27 welded on to close the container. On this lid there is a suction port 32 with a suction pipe for each individual chamber 30 32 'so that all individual chambers can actually be evacuated. Here too the pipes are 32 ' closed by constriction as soon as the Evacuation has been carried out.

There. hot isostatic presses of the multiple sandwich assembly of the Fig. 10 and the rolling out of the resulting bimetal plate is done in exactly the same way as is the processing of the strip 9 in FIG. 8. However, as FIG. 11 shows now the stripe is much wider. The stripe will be as dashed with Lines indicated, not only separated in the middle of the narrow sections 16 ', but also along the centers of the wider sections 17 '. When cutting lengthways several lengths of the bimetallic saw blade material arise at the same time, in the illustrated Trap six. The size of the multiple arrangement is only available by what is available in each case Isostatic pressing and rolling capacity limited.

If one applies to both the band metal and the tooth tip metal Powder perweab det in forming the bimetal assembly is an entire metal container 33 according to FIG. 12 can be used. This container 33 is preferably made of soft Steel and has flat vertical walls 34-34 ', 35-35' and a bottom, not shown. The opposite walls 34-34 'have in this case aligned with one another Slots 56, in which the edges of two separating strips 37 can be used, which the Container in a narrow chamber 38 and two wider chambers 39 of the same size Subdivide cross-sectional dimensions. The powdered tooth tip metal comes in the narrow central chamber and the powdered band metal in the two wider ones outer chambers.

The dividing strip should be made of a metal that is the same Composition has like one of the two pa verized metals or it should ouch a third alloy, which gives the possibility of a good transition zone between the two metals so that the subsequent isostatic hot fretting of the assembly makes the separating strips a permanent part of the bimetallic plate will. Deviating from this, pre-sintered ones can also be used without separating strips dimensioned powder compacts of one or the other metal are used.

As with the previously described embodiments of the invention the container 33 (Fig. 12) closed after filling with a lid 40, the then evacuated and sealed. For the latter purpose there is at the Cover 40, a connection 41 with a suction tube 42.

Here, too, the isostatically hot-pressed bimetal can be rolled out can be started before the walls of the container have been removed. The latter but should be removed before the last roller pass.

In all embodiments of the invention, when assembling the bimetal assembly of the powder metal either in loose, flowable form or come as a preformed compact to be used.

Above was primarily on the high-speed steel M2 Sir the tooth tips and referred to the band metal D68, but other alloys can also be used. For example, high-speed cutting tool steel is suitable for tooth tip metal, Chrome tool steel, semi high speed tool steel, impact resistant tool steel, Cobalt-based tool steel or equivalent modifications. For the strip metal Medium-alloy spring steel, stainless steel, Marage steel or their modifications are suitable.

Regarding the fixed rods t2 (Fig. 3 to 4) of the strip metal let mentions that these are used in the Z'wammenbau der Bimetal group in the following Condition can be: cast, sintered or compacted bars from processed Cast or powder.

An exceptionally important and notable advantage of the invention is that it is now very easy to incorporate additives into the tooth tip metal can affect the strength, ductility, wear resistance, etc., of the tooth tips to enhance. For example, finely divided oxides, nitrides and / or carbides from light, heavy or rare earth elements into the pulverized tooth tip-forming Metal are dispersed without adversely affecting its homogeneity or density, while at the same time in the end product a previously unattained fine grain is achieved. Specific examples of such additives are: Thorium, Ittrium, Itterbium, Cerium, lanthanum, praseodymium, columbium carbide, tantalum carbide, titanium carbide, hafnium carbide, Uranium carbide, lanthanum carbide, cerium carbide, boron nitride, zirconium nitride, aluminum oxide, zirconium diboride.

The dispersing of the selected additives in the powdered tooth-forming Metal can be easily carried out in a grinding process or the like. In such procedure is both the additive and the rest of it all Dispersing in the powdered state. As it is isostatic pressing during biting not too macroscopic segregations and only very minimal microsegregations the powder metal comes, the ductility of the finished product at ambient temperature only minimally affected by segregation. If, on the other hand, you use the additives in would introduce a certain gas-metal alloy by conventional fusing, if there were significant segregations Another very important advantage of the invention it follows that at least one of the two metals is sioh when assembled of the bimetal group is in the powdered or sintered powdery state. This makes it possible to monitor the chemical activities in the transition zone of the area between the two metals. The meaning of these Correctness results from the following explanation of the Fig.

13 and 14.

When metals of different chemical composition lie next to each other are heated, the mixing and Znterdiffusion to be expected is a given Element 1 as shown in FIG. In developing this Invention, however, it was found that the narrowing and diffusion of the neighboring Fabrics here run completely differently than expected. Fig. T4 shows what actually happens.

The particular properties of those specifically used according to the invention Elements, namely carbon in strip steel and tooth tip steel and the strong ones carbide-forming elements, such as molybdenum, tungsten, vanadium and ohrom, which are in the high-speed cutting steels lead to the unusual phenomenon that 14 reproduces. As shown, Alloy A has a stronger affinity to the element X as the alloy B even if the element x in the alloy mg is present in larger quantities. As a result, the boundary layer is formed on one side a zone in which the amount of the element X is greatly reduced and on the opposite one Side of the boundary layer a zone which is enriched with respect to the element X.

In the case of a bimetal saw blade blank, this manifests itself Philnomen as a decarburized zone in the part of the transition area that forms the band Steel mustache is. The carbon loss in this decarburized Zone could cause a weakening precisely where strength is needed, and on the other hand, the carburized zone in the part of the transition area that is adjacent to the tooth tip steel have an excessively great hardness, however Unfortunately, it is coupled with a low ductility that increases in service could lead to the tip of the tooth becoming detached.

However, since at least one of the two metals is used when assembling the 3imetal group is in the powdery state, one can have the aforementioned disadvantageous consequences avoid by grading the composition of each of the two steels uniformly, by using a separating strip mm of a compensating composition or by applying both corrective actions. . The use of powder metal is here the key.

From the above description and the accompanying drawings It follows that the invention is a completely new and economical route for the manufacture of bimetal band saw bands and that according to the invention manufactured bimetal band saw blades are superior to all previously known.

For the person skilled in the art, it is also obvious that compared to the illustrated and the embodiments described, numerous modifications are possible.

Claims (18)

Expectations 1. Process for the production of bimetal band saw blades, the band part made of a durable material, hereinafter referred to as strip metal, and its tooth tips consist of a well-cutting material, hereinafter referred to as tooth tip metal, characterized in that at least one cuboid space 14) between with Distance. parallel and aligned strip metal blocks (12) with powdery Tooth tip metal (15) filled and the bimetal assembly thus created with a airtight envelope (13) is provided, which is evacuated, sealed and hot isostatic presses until the powdery tooth tip metal (15) compacts and with the band metal blocks (12) is combined into a bimetal plate (Fig. 6) that the bimetal plate (Fig. 6) is further processed into an elongated bimetal strip (9; Fig. 8), that then the bimetallic strip (9) along the consisting of tooth tip metal, between wider middle sections made of strip metal side sections (17) (16) is cut lengthways to produce a starting material (Fig. 2) from which then the bimetal band saw blades (Fig. 1) manufactured in a manner known per se will 2. The method according to claim 1, characterized in that the strip metal body when the powdered tooth tip metal is introduced into the Block-shaped spaces machined solid blocks or consisting of powder firmly enclosed bodies or castings or pre-sintered or pressed powder bodies are. 3. The method according to claim 1 and 2, characterized in that the Press container (25, 35) encloses the entire bimetal construction cap. 4. The method according to claim 1 and 2, characterized in that at Use of solid blocks as strip metal, the covering only of plates (13,13 ' is formed, which enclose the tooth tip metal powder (15) containing space (14) (Fig. 3). 5. The method flat to claim 4, characterized in that the the Press container forming additional plates (13, 13 ') on the side and bottom surfaces the hand metal rods (12) are attached, preferably welded. 6. The method according to claim 5, characterized in that the Further processing of the bimetal plate rolling takes place, in which the seams isohen the two different metals perpendicular to the roll axis are directed (Fig. 7). 7. The method according to claim 1 to 6, characterized in that the Press container either before rolling or at least before the last passage of walts is removed from the bimetal plate. 8. The method according to claim 1 bit 7, characterized in that when Longitudinal cutting of the bimetal strip along the central tooth tip metal section also the flaked sections of the strip metal parallel to the center cut in a given Distance to be lined. 9. The method according to claim 1 to 8, characterized in that one Multiple bimetal assembly in multiple sandwich form in a common container (25) is hot isostatically pressed and that after rolling, not only the tooth tip metal strip (16 ') but also the strip metal strips (17') are split in the longitudinal direction (Fig. 10 and 11) 10. The method according to claim 9 «characterized in that that all chambers (30) for the powdery tooth tip metal via separate Suction connections (32 ') are evacuated. 11. The method according to claim 9 and 10, characterized in that the strip metal blocks (12) in a row in a cuboid press container (25) arranged and attached to the bottom (28) of the container (25) spacers (29) who are aligned. 12. The method according to claim 1 to 11, characterized in that between two different powder metals, separating strips made of one metal are arranged which has the same composition as one of the two metals. 13. The method according to claim 1 to 11, characterized in that between two different powder metals separating strips from a Netall arranged be, which has a composition that has a more favorable transition between the two metals. 14. The method according to claim 1 bus 13, characterized in that the band saw blade blanks (Fig. 2) annealed stress-relieved, straightened and wet be brought that in the Gegitihten state in the edge part of the tooth tip metal (8) Teeth (5) are milled in such a way that the tooth roots are still formed by the band metal (4) and that the teeth are then straightened, hardened and tempered. 15. Bimetal band saw blade produced by a method according to claims 1 to 14 Made of a metal that bids the back of the saw band and the tooth roots with good fatigue strength and tooth tips made of good cutting material, characterized in that the Tooth tip metal connected to the rest of the strip metal by powder metallurgy is. 16. Bimetal band saw blade according to claim 15, characterized in that that the transition zone between the two different metals is free of chemical Discontinuities is. 17. Bimetal band saw blade according to claim 15 and 16, characterized in that that the tips of all teeth have an extraordinarily large uniform density and have an extremely essentially segregation-free grain. 18. Bimetal band saw blade according to claim 15 to t7, characterized in that that in the case of tooth tips formed from high-speed steel in the high-speed cutting steel in an amount between a trace and 30 atomic percent additives from the following Group dispersed were: thorium, yttrium, ytterbium. Cerium, lanthanum, praseodymium, Columbium carbide, tental carbide, hafnium carbide, uranium carbide, lanthanum carbide, cerium carbide, Boron nitride, zirconium nitride, aluminum oxide and zirconium diboride.